﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.IO;
using System.Security.Cryptography;
using System.Text;


namespace LIMS.Common
{
    /// <summary>
    /// 加解密封公共类
    /// </summary>
    public class EncryptHelper
    {
        /// <summary>
        /// DES 加密(数据加密标准，速度较快，适用于加密大量数据的场合)
        /// </summary>
        /// <param name="EncryptString">待加密的密文</param>
        /// <param name="EncryptKey">加密的密钥</param>
        /// <returns>加密后的字符串</returns>
        /// <example>
        /// 定义等待加密的字符串：
        /// <code>String strSource = "tyl_.13795731409";</code>
        /// 定义加密、解密的密匙字符串，长度限制为八个字符
        /// <c>String DESEncrypt = @"id_+>.\(";</c>
        /// 输出加密后的字符串
        /// <code> Console.WriteLine(EncryptHelper.DESEncrypt(strSource, DESEncrypt));</code> 
        /// </example>
        public static string DESEncrypt(string EncryptString, string EncryptKey)
        {
            if (string.IsNullOrEmpty(EncryptString) || string.IsNullOrEmpty(EncryptKey))
            {
                throw (new Exception("密文、密匙均不得为空"));
            }
            if (EncryptKey.Length != 8)
            {
                throw (new Exception("密钥必须为8位"));
            }
            byte[] m_btIV = { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF };
            string m_strEncrypt = "";
            DESCryptoServiceProvider m_DESProvider = new DESCryptoServiceProvider();
            try
            {
                byte[] m_btEncryptString = Encoding.Default.GetBytes(EncryptString);
                using (MemoryStream m_stream = new MemoryStream())
                {
                    using (CryptoStream m_cstream = new CryptoStream(m_stream, m_DESProvider.CreateEncryptor(Encoding.Default.GetBytes(EncryptKey), m_btIV), CryptoStreamMode.Write))
                    {
                        m_cstream.Write(m_btEncryptString, 0, m_btEncryptString.Length);
                        m_cstream.FlushFinalBlock();
                        m_strEncrypt = Convert.ToBase64String(m_stream.ToArray());
                    }
                }
            }
            catch (IOException ex)
            {
                throw ex;
            }
            catch (CryptographicException ex)
            {
                throw ex;
            }
            catch (ArgumentException ex)
            {
                throw ex;
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                m_DESProvider.Clear();
            }

            return m_strEncrypt;
        }

        /// <summary>
        /// DES 解密(数据加密标准，速度较快，适用于加密大量数据的场合)
        /// </summary>
        /// <param name="DecryptString">待解密的密文</param>
        /// <param name="DecryptKey">解密的密钥</param>
        /// <returns>返回解密后的字符串</returns>
        /// <example>
        ///  待解密的字符串 
        ///  <c> String DESDecryptSource = @"xg40niWG9BFxPjhFzuaR0ChQA4/fundi";</c> 
        ///  解密字符串用法：
        ///  <c> Console.WriteLine(EncryptHelper.DESDecrypt(DESDecryptSource, DESEncrypt));</c>
        /// </example>
        public static string DESDecrypt(string DecryptString, string DecryptKey)
        {
            if (string.IsNullOrEmpty(DecryptString) || string.IsNullOrEmpty(DecryptKey))
            {
                throw (new Exception("密文、密匙均不得为空"));
            }
            if (DecryptKey.Length != 8)
            {
                throw (new Exception("密钥必须为8位"));
            }
            byte[] m_btIV = { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF };
            string m_strDecrypt = "";
            DESCryptoServiceProvider m_DESProvider = new DESCryptoServiceProvider();
            try
            {
                byte[] m_btDecryptString = Convert.FromBase64String(DecryptString);
                using (MemoryStream m_stream = new MemoryStream())
                {
                    using (CryptoStream m_cstream = new CryptoStream(m_stream, m_DESProvider.CreateDecryptor(Encoding.Default.GetBytes(DecryptKey), m_btIV), CryptoStreamMode.Write))
                    {
                        m_cstream.Write(m_btDecryptString, 0, m_btDecryptString.Length);
                        m_cstream.FlushFinalBlock();
                        m_strDecrypt = Encoding.Default.GetString(m_stream.ToArray());
                    }
                }
            }
            catch (IOException ex)
            {
                throw ex;
            }
            catch (CryptographicException ex)
            {
                throw ex;
            }
            catch (ArgumentException ex)
            {
                throw ex;
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                m_DESProvider.Clear();
            }

            return m_strDecrypt;
        }

    }
}
